Crop Image trim: decode print-size rasters, and leave CMYK images alone

Trim decoded the image with the decoder's default 512 MB allocation limit, so
a 300 ppi roll (6614 x 59055 px, 1.56 GB as RGBA) that opens fine failed with
"the image's pixels can't be read". It now decodes with the allowance opening
already has (MAX_RASTER_ALLOC: 2 GB, 512 MB on the web). A CMYK image, kept as
its ink amounts, has no alpha: trim leaves it alone (trimmed: false) instead
of failing to decode it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/fileio/load.rs

@@ -392,7 +392,7 @@ pub(super) fn new_from_template(s: &mut Session, p: &Value) -> Result<Value> {
 /// The most memory decoding one image may take: a 60 in print sheet at 300 ppi (18000 × 6600 px)
 /// is ~475 MB as RGBA, past the decoder's 512 MB default once it is converted. The web app keeps
 /// that default: wasm32 has 4 GB to address and aborts when an allocation fails.
-const MAX_RASTER_ALLOC: u64 = if cfg!(target_arch = "wasm32") { 512 << 20 } else { 2 << 30 };
+pub(crate) const MAX_RASTER_ALLOC: u64 = if cfg!(target_arch = "wasm32") { 512 << 20 } else { 2 << 30 };
 
 /// Decode an image's header (and, for formats stored as PNG, its pixels). CMYK TIFFs are kept as
 /// they are, with their ink amounts ([`ImageBlob::cmyk`]); CMYK TIFFs with an alpha channel, which

crates/engine/src/cmd/fileio/mod.rs

@@ -28,6 +28,7 @@ pub mod eps;
 mod export;
 pub(crate) mod imagemap;
 mod load;
+pub(crate) use load::MAX_RASTER_ALLOC;
 mod metafile;
 mod native;
 pub mod pdf;

crates/engine/src/cmd/menucmds.rs

@@ -625,7 +625,18 @@ fn trim_image(s: &mut Session, id: NodeId, im: ImageObject) -> Result<Value> {
     const C: &str = "object.cropImage";
     let st = s.doc()?;
     let blob = st.doc.images.get(&im.key).ok_or_else(|| bad(C, "the image's pixels are missing"))?;
-    let px = image::load_from_memory(&blob.bytes).map_err(|_| bad(C, "the image's pixels can't be read"))?.to_rgba8();
+    // A CMYK image (kept as its ink amounts) has no alpha: nothing to cut.
+    if blob.is_cmyk() {
+        return Ok(json!({ "id": id.0, "width": im.width, "height": im.height, "trimmed": false }));
+    }
+    // Print rasters run to gigabytes decoded: the same allowance opening them has.
+    let mut reader = image::ImageReader::new(std::io::Cursor::new(blob.bytes.as_slice()))
+        .with_guessed_format()
+        .map_err(|_| bad(C, "the image's pixels can't be read"))?;
+    let mut limits = image::Limits::default();
+    limits.max_alloc = Some(crate::cmd::fileio::MAX_RASTER_ALLOC);
+    reader.limits(limits);
+    let px = reader.decode().map_err(|e| bad(C, format!("the image's pixels can't be read: {e}")))?.to_rgba8();
     let (w, h) = px.dimensions();
     let (mut x0, mut y0, mut x1, mut y1) = (w, h, 0, 0);
     for (x, y, p) in px.enumerate_pixels() {